title: Protein stability and enzyme activity at extreme biological temperatures.
abstract: Psychrophilic microorganisms thrive in permanently cold environments, even at subzero temperatures. To maintain metabolic rates compatible with sustained life, they have improved the dynamics of their protein structures, thereby enabling appropriate molecular motions required for biological activity at low temperatures. As a consequence of this structural flexibility, psychrophilic proteins are unstable and heat-labile. In the upper range of biological temperatures, thermophiles and hyperthermophiles grow at temperatures > 100 °C and synthesize ultra-stable proteins. However, thermophilic enzymes are nearly inactive at room temperature as a result of their compactness and rigidity. At the molecular level, both types of extremophilic proteins have adapted the same structural factors, but in opposite directions, to address either activity at low temperatures or stability in hot environments. A model based on folding funnels is proposed accounting for the stability-activity relationships in extremophilic proteins.
authors.affiliation: Laboratory of Biochemistry, Centre for Protein Engineering, Institute of Chemistry B6a, University of Liège, B-4000 Liège, Belgium. gfeller@ulg.ac.be
authors.forename: Georges
authors.initials: G
authors.lastname: Feller
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D017510:Protein Folding; D055550:Protein Stability; D016963:Thermus thermophilus / Q000201:enzymology / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004798:Enzymes